1. Field of the Invention
The invention relates to access control systems and more particularly to a radio frequency (RF) access control system and method.
2. Description of the Prior Art
Access control relates to the management of an entity's ability to legitimately pass through a gateway in an authorized manner. Historically, access control has been handled in many different ways including lock and keys, guards, passwords, and biometrics.
One popular method of access control involves the use of corresponding transceivers that communicate with each other to indicate that an entity is authorized to pass through the gateway. In use, a first transceiver (e.g., transmission initiator) remains stationary at the gateway. A second transceiver (e.g., receiver transponder) is carried by the entity seeking access through the gateway. As the second transceiver approaches the first transceiver, the pair of transceivers communicates with each other to indicate that entity is authorized to enter the gateway.
One type of transceiver pair access control system utilizes radio waves to communicate between transceiver pairs. Current technologies for this type of system operate in several frequency bands including the 13.56 MHz, 915 MHz, and 2.45 GHz bands. These types of systems are generally referred to as far field because the transmissions radiate into free space
Another type of transceiver pair access control system utilizes near field magnetic induction to communicate between transceiver pairs. Current technologies for this type of system operate in several frequency bands including frequencies between 120 KHz-135 KHz. In the 120 KHz-135 KHz band, communication between devices is limited to distances of less than 10 cm. These types of systems are generally referred to as near field because transmissions are contained within a localized magnetic field or communication “bubble” that surrounds a communication device such as a radio, headset, or microphone.